It is often desirable to axially adjust the position of the steering wheel of a vehicle. The first advantage in having the ability to axially adjust the steering wheel is the comfort gained by having the steering wheel at an optional position as a function of the operator's arm length. The operator may sit comfortably close to or far from the steering wheel. The second advantage in having axial adjustment is the increased ease in entering and exiting the driver's seat. Large operators need more room with which to enter and exit the driver's seat, but do not necessarily need the space between themselves and the steering wheel once they are in the driver's seat.
Several patents disclose telescopic helms. These include: the U.S. Pat. No. 614,944 to Gaylor, issued Nov. 29, 1898; U.S. Pat. No. 973,806 to Noble, issued Oct. 25, 1910; U.S. Pat. No. 4,347,757 to Martin, issued Sept. 7, 1982; U.S. Pat. No. 4,418,582 to Martin, issued Dec. 6 1983; and U.S. Pat. No. 4,572,023 to Euler, issued Feb. 25, 1986. These patents disclose various designs embodying cam surfaces producing an outwardly directed force that locks the steering wheel shaft axially in place. These designs are all deficient in two aspects. First, these designs necessitate a sheath extending the length of the adjustable portion of the helm. This adds material costs by adding a sheath, and support and alignment structure to the design. Second, since the sheath is an outer structure, it is prone to crimps and dents which will lessen the range of the axial movement and/or the effectiveness of the outward force being placed on the sheath.